Timing device



Patented Feb. 2, 1932 PATENT OFFICE JOHN MILTON LUERS, 0F DETROIT, MICHIGAN TIMING DEVICE Application led November 7, 1929. Serial No. 405,524.

This invention relates to improvements in timing devices and refers more particularly to timing devices for furnaces.

At the present time it is customary to udge when high speed steel hasbeen heated to the requiredtemperature for hardening by its appearance, consequently` a highly skilled tool hardener is required for t-he work.

'When a large number of similar pieces are to be hardened which necessitate many consecutive `furnace charges it is found that `though the time actually needed to heat each charge is the same the tool hardener will allow some charges to remain in the furnace longer than others ;-this sometimes results in considerable loss` Obviously it is not feasible for a hardener to stand with a stop watch in hishands. Y

This invention `therefore aims to provide a timingvdevice wherein a pointer is automatically set in motion by the closing of the furnace door so that as long as the speed of loading and unloading the furnace remains constant uniformity in temperature of the work when unloaded will result.

Another object of the invention is to provide' a timing device wherein the pointer 'is automatically returned to its starting position when the furnace door is opened, and wherein the pointer is held stationary at the starting position as long as the door remains open.

With these and other objects and advantages in view which will become apparent hereinafter, the invention is more fully described with the aid of the accompanying drawings, in which:

Figure'l illustrates a. front elevation of al leys 5 and 6, and the latter are both revolvably mounted on a bracket 7.

The timing device is generally referred to by the ordinal 8, and is usually mounted under the furnace. In the present instance the device is arranged `on a base plate 9 which forms a portion of the furnace supporting frame 10.

Mounted on the plate 9 is a suitable gear box 11 having bearings 12 thereon to carry a shaft 14. Means are provided for driving the latter, which, in this case, consist of an electric motor 15 the shaft 15a of which has av worm 16 thereon which meshes with a worm-wheel 17 fixed on the shaft 14. Other driving means may however be employed when desired.

A tubular member 18, secured around one extremity of the shaft 14 as by a taper key 19, has a closed end 18a!l from which an extension 20 projects in axial alignment with the said shaft, and around the open end of the member 18 a flange 21 is provided. A spool 22 is loosely mounted around the member 18 and at its extremities is of substantially thesame diameter as the flange 21. Between the adjacent faces of the spool 22 and the flange 21 is a washer 23 usually made of leather. Slidable axially on the inner end of the extension 20 is arflange 24 which is caused to rotate with the member 18 by a pin 25 which projects from the closed end 18a of the member and extends into an aperture 26 in the flange 24. Between t-he adjacent faces of the latter and the spool 22 another washer 27, also preferably made of leather, is arranged.

On the outer end of the extension 2O is a washer 28 held against outward movement by a nut 29, A helical spring 30 is arranged around the extension 2() and has one extremity resting against the washer 28 and its opposite end bearing against the fiange 24, thereby forcing the latter against the washer 27' and causing said washer to bear against the adjacent face of the spool 22. Thus the tension of the spring 30 tends to impart a frictional drive to the spool 22 as'long as the shaft 14 turns.

A radial passage 31 is formed in the intermediate spool portion 22a which is of course of reduced diameter, and from one side of the spool a tapped hole 32 is provided which extends into the passage 31. One extremity of a cable 33 is placed in the passage 31 and is securely held by a screw 34 in threaded engagement with the tapped hole 32. The opposite end of the cable l33 is fastened to. a screw 35a in threaded. engagement with a turnbuckle 35, and to the other end of the latter a coil spring 36 is secured. 'From the latter a cable 37 extends around a pulley 38 generally mounted by the side of the pulley 6 on the bracket 7.

On the furnace 1 a bracket 39 is secured on which one end of a'flexible lever 40 is pivotally mountedabove va horizontal axis. 4l designates another bracket which extends from the side of the furnace and has a hold ing device 42 projecting upwardly therefrom. The latter is provided with an enlarged head having a horizontal bearing surface 42a on its underside which is spaced from the top of the bracket 41 by a shank 426. One end of each of the cables 4fand 37 is secured to the lever 40, and depending from the latter is a member 43 which carries a balance Weight 44.' The latter is of `Vsuch weight that when the door 2 is openand the spring 36 is distended, as shown in Figure l, the tendency is for the weight to' raise and the door to close. The lever 40 ismade flexible so that it may be flexed sufficiently to .pass around one side of the head of the holding device 42. It then vreassumes its normal sha-peand bears against'the surface 42athereby retaining the door 2 in open position and the spring distended. The tension of the spring 36 then holds the cable 33 against movement and consequently the spool 22 against rotation. As soon asy the klever is released from the holding device 42 the lever and the weight 44 move up- Wards. As the weight 44 is raised and the door 2 moves downwards tension on the spring -36 is first released and then some of the cable 33 drops into the slackrposition shown at 33e. When tension on the spring 36 ceases the spring 30 causes rotation both of thespool 22 and of a radial pointer'45 which projects from the spool.

Mounted on the base plate 9 is a bracket 46 which supports an annular dial 47 around the periphery of which graduations may be provided. Movable around the periphery of the'dia-l is an indicator 48 which may be `set at any desired position by a screw 49.

50 denotes a stop projecting forwardly from the dial 47 against which the pointer 45 rests when in zero position; When the pointer strikes thestop further rotation of the spool 22 is prevented.

When the `outer end of the lever 4() is pulled downwards to raise the door 2, the cable 37 Vfirst pulls the cable 33 and causes the spool 22 to rotate in the opposite direction to that in which it is normally driven until the pointer 45 strikes the stop 50, then continued movement of the lever distends the spring 36 so that the latter exerts sufficient pull on the cable 33 to offset the effort of the spring 30 and the flanges 24 and 21 to turn the spool. The latter therefore remains motionless until the outer end of the lever 40 is again raised and the door 2 closed when, as previously stated, tension on the spring 3G ceases and a portion of the cable 33 drops into the slack position indicated at 33a thereby permitting the spring 30 and the flanges 24 and 21 to again cause rotation of the `spool 22.

From the foregoing it will be clearly seen that as the door 2 is closed vthe pointer 45 commences to turn, and that the action of opening the door returns the pointer each:

time to its Zero position. Further the pointer is held in its zero position until the door is closed.

As the speed of rotation of the shaft 14 is constant it follows that a uniform speed is' maintained by the spool 22 when the latter is free toturn, consequently a fixed time interval always occurs lbefore the pointer 45 reaches a given posit-ion. And if a uniform speed of loading and unloading the lcharge from the furnace is maintained ai predetermined heat will always be obtained. It may also be remarked that in small high speed steel heating furnaces for which the yinvention is primarily intended only one or two trays or pieces of work are usually inserted at a time, so that substantially uniform loading and unloading times can be readily maintained.

While in the foregoing the preferred embodiment of the invention has been described and shown, it is understood that the invention is susceptible to such alterations and modifications as fall Within the scope of the appended claims.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a timing device, the combination of a furnace having a door adapted to be opened, a spool, means tending to turn said spool in one direction at a constant speed, a cable one extremity of which is secured to said spool adapted to be wound around said spool by the rotation of the latter, said cable being connected to the door so that the opening of the latter turns' the spool in the direction opposite to that in which said means tend to turn it, a )ointer on said spool, a dial in front of which said pointer turns, and means which holds the cable and spool stationary when the door is open. t

2. In a timing device, the combination of a furnace having a vertically movable door, a balance weight connected to said door and adapted to move with butin the opposite direction to the door, a spool, means tending to turn said spoolat a constant speed in one direction, a cable having one extremity secured to said spool and its opposite end to said balance weight, said cable being adapted to be wound around the spool when the latter is turned in the direction in which said means tend to turn it, and downward movement of the balance weight being adapted to unwind said cable by turning the spool in the opposite direction.

3. In a timing device, the combination of a furnace having a vertically movable door, a balance weight connected to said door adapted to move with but in the opposite direction yto the door, a spool, means tending to turn said spool at a constant speed in one direction, a cable having one extremity secured to said spool and its opposite end to said balance weight, said cable being adapted to be wound around the spool when the latter is turned in the direction in which said means tend to turn it, downward movement of the balance weight being adapted to unwind said cable by turning the spool in the opposite direction, and means limiting the unwinding of the cable and the rotationof the spool in the direction opposite to that in which said means tend to turn it.

4. In a timing device, the combination of a furnace having a vertically movable door, abalance weight adapted to move with but in the opposite direction to the door, a cable connected to said door and to said balance weight, a spool, means tending to drive said spool at a constant speed in one direction, a second cable having one extremity secured to 'said spool and its opposite end to said first named cable, said second cable being adapted to be wound around the spool when the latter is turned in the direction in which said means tend to turn it, downward movement of the balance weight being adapted to unwind said cable by turning the spool in the opposite direction, and said second cable holding the spool against rotation when the door is open.

5. In a timing device the combination of a furnace, a door verticall movable thereon, a balance weight, a ca le connecting the weight with the door so that one moves upwards as the other moves downwards, a spool, frictional driving means adapted to turn the spool in one direction at a constant speed, a second cable connected to said spool and to said balance Weight which is wound around the spool when the latter is turned in its driven direction, the downward movement of the balance weight being adapted to unwind said second cable and rotate the spool in the opposite direction to that in which it is frictionally driven, and a spring on said second cable which holds the spool against rotation as long as the door is open.

6. In a timing device, the combination of a shaft rotated at uniform speed in one direction, a spool, friction means adapted to turn the spool by the rotation of said shaft, a pointer on said spool, a dial in front of which said pointer is adapted to turn, a furnace, a door movable thereon, a cable con' nected to said door `and said spool which is wound around said spool lby the rotation of the latter, and for stopping the rotation of Vsaid spool when the door is opened, and

spool from the rotation of said shaft, a

pointer on said spool, a dial in front of which said pointer is adapted to turn, a furnace, a door movable thereon, a stop on said dial against which the pointer rests when in zero position, a cable connected to said door and said spool, and means for turning the spool in the direction opposite to that in which it is turned by said shaft as the door is opened until the pointer registers with the stop.

8. In a timing device, the combination of a shaft rotated at uniform speed in one direction, a spool, means tending to turn the latter with said shaft, a pointer on said spool, a fixed dial in front of which said pointer turns, a cable one end of which is secured to said spool, a furnace, a door movable thereon, a balance weight movable with but in the opposite direction to said door, and said cable being connected to said balance weight so that downward movement of the latter turns said spool in the direction opposite to that in which it may be turned by said shaft.

9. In a timing device, the combination of a shaft, a spool, means tending to turn the latter, a pointer on said spool, a iixed dial in front of which said pointer is adapted to turn, a cable one end of which is secured to said spool, a spring connected to said cable, a furnace, a door thereon, and a balance weight movable with but in the opposite direction to said door, said spring being also connected to said balance weight so that downward movement of the latter distends said spring and holds said spool against rotation in the direction in which said means tends to turn it.

10. A timing device comprising a furnace, a door movable thereon., a balance weight connected to said door adapted to move with said door, means for holding said door in open position, in combination with a spool, a pointer thereon, means tending to turn said spool at uniform speed in one direction, a dial in front of which said pointer is adapted to turn, means for turning said spool and pointer in the direction opposite to that in which they are turned by said rotating means until the pointer is returned to a predetermined position as the door is opened,

and means for holdin'gesaid spool and .pointer against rotationv as long 'as the door remains i open.

11. As a new article of manilfactre, a timing device for hardening furnaces, comprising a furnace, a door thereon, a friction driven spool, a cableconnected to saidV spool end togsaid door, seid cable permitting rotation of said spool when the door is dosed, and preventing rotation of the spool When the door is open, aV pointer carried by said yspool, and e dial in front ofY which said pointer turns. v n

' JOHN MILTON LUERS.' 

